This is a simple DC 0-10 volt controlled PWM circuit.
Useful for small DC motor control, LED or filament lamp driver
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DMX to 0-10 VDC converter
Convert 0-10VDC to DMX512 protocol.
Isolated DMX splitter.
DMX to PWM servo
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Application circuits for Encoder and Decoder
Notes about DMX 512 protocol
Trouble shooting guide.
Warranty and disclaimer.		 T1 is an PNP transistor that provides a constant current source for C1. 
The 555 timer uses the ramp generated at the collector of T1 to time the discharge of C1.
Resistors R3 and R4 control the charge rate of C1 and therefore the output frequency. 

R1 is used the set the peak voltage of the ramp.
If precise tolerance is required then a 10 turn trim pot is recommended for R2. A 2.5K trim pot would be sufficient. A much higher pot will make to adjustment less precise.

The ramp is then fed to the - input of a LM339 comparator.
The 0-10 VDC from the decoder is fed to the + input of the comparator.
When the 0-10 VDC voltage on + input is higher than the instantanious ramp voltage the output will be high.

A comparator is required to achieve fast switching rates. Most common Op Amps like the LM324 have much to high slew rate for this application.
 

Click here to download the schematic in PDF format
 


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